…LOWER MO AND OH VALLEY REGION THIS AFTERNOON INTO TONIGHT…
AN INITIAL LEE CYCLONE IN NW KS WILL DEVELOP EWD TO W CENTRAL MO BY THIS EVENING…AND THEN CONTINUE DEEPENING WHILE PROGRESSING EWD OVER THE LOWER OH VALLEY TONIGHT. THE SURFACE CYCLONE WILL DEEPEN IN RESPONSE TO THE EWD MOVEMENT OF A PRONOUNCED MIDLEVEL SHORTWAVE TROUGH FROM CO/WY…AS PHASING BEGINS TO OCCUR LATE TONIGHT WITH A SEPARATE NRN STREAM TROUGH OVER THE UPPER MS VALLEY. MODEST LOW-LEVEL MOISTURE RETURN WILL OCCUR WITHIN THE WARM SECTOR OF THE CYCLONE TODAY…AS BOUNDARY LAYER DEWPOINTS IN THE LOW-MID 50S SPREAD NWD/NEWD FROM E TX. THE MAGNITUDE OF THE MOISTURE RETURN WILL BE INHIBITED BY THE INFLUENCE OF A SRN STREAM SHORTWAVE TROUGH AND ASSOCIATED DEEP CONVECTION ACROSS THE N CENTRAL GULF OF MEXICO.

THE INCREASE IN LOW-LEVEL MOISTURE…IN COMBINATION WITH SURFACE HEATING…WILL CONTRIBUTE TO THE DEVELOPMENT OF WEAK BUOYANCY IN THE WARM SECTOR ACROSS CENTRAL/NRN MO THIS AFTERNOON. FOCUSED LOW-LEVEL ASCENT ALONG THE SURFACE FRONT IMMEDIATELY IN ADVANCE OF THE DEEPENING SURFACE CYCLONE WILL SUPPORT THUNDERSTORM DEVELOPMENT ACROSS NRN MO IN THE 22-00Z TIME FRAME. CONVECTION WILL THEN SPREAD EWD/ESEWD TO THE LOWER OH VALLEY OVERNIGHT…WITH ADDITIONAL DEVELOPMENT SWWD ALONG THE COLD FRONT THIS EVENING INTO SW MO. WHILE SBCAPE IS ONLY EXPECTED TO REACH ABOUT 500 J/KG…DEEP-LAYER VERTICAL SHEAR WILL BE SUFFICIENTLY STRONG FOR SOME SUPERCELL RISK WITH THE INITIAL CONVECTION ACROSS NRN/CENTRAL MO THIS EVENING…AND MORE LINEAR CONVECTION FARTHER SW ALONG THE COLD FRONT. ISOLATED DAMAGING GUSTS AND MARGINALLY SEVERE HAIL WILL BE POSSIBLE WITH ANY SUPERCELL STRUCTURES… WHILE STRONG/DAMAGING GUSTS ARE THE MAIN CONCERN WITH THE NARROW LINE OF CONVECTION ON THE COLD FRONT. THOUGH LOW-LEVEL SHEAR WILL INCREASE TONIGHT AS A SWLY LLJ STRENGTHENS FROM SRN MO TO THE LOWER OH VALLEY…CONVECTION WILL BECOME LARGELY ELEVATED IN AN ENVIRONMENT WITH WEAK BUOYANCY. THUS…THE WIND/HAIL THREAT SHOULD DIMINISH GRADUALLY WITH EWD EXTENT FROM NRN/CENTRAL MO THIS EVENING.

…N CENTRAL/NE GULF COAST THROUGH TONIGHT…
THE SRN STREAM TROUGH OVER THE NW GULF OF MEXICO WILL BEGIN TO ACCELERATE EWD AND WEAKEN AS THE NRN STREAM WAVE AMPLIFIES BY TONIGHT OVER THE LOWER MO/OH VALLEY REGION. WIDESPREAD CONVECTION IS ONGOING S OF LA…WITHIN THE CORRIDOR OF RICHER LOW-LEVEL MOISTURE/BUOYANCY. HOWEVER…THERE WILL BE LITTLE SURFACE REFLECTION OF THE MIDLEVEL TROUGH…SUCH THAT THE RICHER MOISTURE AND ASSOCIATED THUNDERSTORM RISK WILL NOT SPREAD INLAND MUCH BEYOND THE IMMEDIATE N CENTRAL/NE GULF COAST THROUGH TONIGHT.